Activity and Interactions of Liposomal Antibiotics in Presence of Polyanions and Sputum of Patients with Cystic Fibrosis - Recent Advances in Microbiology - page 85

the antibiotic formulations during a 3 hr pre-incubation first. The free and liposomal
tobramycin at 2 mg/l killed all ATCC 27853 strain within 3 hr, while the liposomal
and free polymyxin B eradicated bacteria at 1 mg/l and 2 mg/l, respectively. The bac-
tericidal activity for both groups of antibiotics in the presence of DNA, F-actin, LPS,
and LTA at the concentrations of 125 to 1,000 mg/l is shown in Figure 1. The activities
of free and liposomal antibiotics were strongly inhibited and liposomal formulations
tended to display lower antibiotic inhibition.
Figure 1. Bactericidal activity and inhibition of antibiotics by DNA, F-actin, LPS, and LTA. A)
Bactericidal concentrations of free tobramycin (F-TOB) and liposomal tobramycin (L-TOB) were
incubated in presence of LPS/LTA (1 to 1,000 mg/l). B) Bactericidal concentrations of free polymyxin
B (F-PMB) and liposomal polymyxin B (L-PMB) were incubated in presence of DNA/F-actin/LPS/
LTA (125 to 1,000 mg/l). Growth controls are represented at 0 hr, and 3 hr. Comparisons between
free and liposomal formulations were made by ANOVA one-way post t-test, and P-values were
considered significant when (**) p<0.01, (***) p<0.001.